Fuel-feeding device for internal-combustion engines



Nov. 16. 1926 v 1,607,399

R. HILDEBRAND FUEL FEEDING DEVICE FQR INTERNAL COMBUSTION ENGINES Filed August 16, 92

I G 9 M A TTOP/YEVS Patented Nov. 16, 1926.

UNITED STATES "PATENT OFFICE.

REINHARD HILDEBRAND, OF WEBSTER GROVES, MISSOURI, ASSIGNOR TO FULTON IRON WORKS COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF DELAWARE.

FUEL-FEEDING DEVICE roa- INTERNAL-COMBUSTION ENGINES.

Application filed August 16, 1924. Serial No. 732,490.

' more particularly to a fuel-feeding device adapted for use in an engine of the Diesel type wherein liquid fuel is atomized in the combustion chamber. To obtaln the maximum efliciency, the entire charge of liquid fuel shouldbe injected in a finely divlded condition to form a mist in the highly heated compressed air in the combustion chamber. Heretofore measured charges of liquid fuel have been 'forced under a very high pressure through a fuel-atomizing nozzle adapted to form the desired mist when the liquid fuel is moving at the required velocity through the atomizing elements, but it is obvious that a non-uniform velocity will result in a non-uniform atomization of the fuel. Consequently, to obtain the highest eiiiciency, the fuel should be transmitted through the atomizing'nozzle at a substantially unlform velocity.

Prior to this invention, quick-acting pumps have been used to force the-charges of liquid fuel through the atomizers in the combustion chambers. The pump plungers perform their functions during very brief periods of time, and in fact the fuel-feeding operation is so brief that it results in an irregular condition, which-I believe was not recognized prior to the presentinvention. In the ordinary fuel-feeding system, the condition to which I will refer causes the liquid fuel to pass through the atomizing nozzle at a non-uniform velocity, and owing to the variation in the speed and pressure, some of the liquid fuel issues from the nozzle in the form of relatively large drops.

which are not entirely consumed in the combustion chamber.

Even if it is assumed that the plunger of the ordinary fuel-feeding pump moves at a uniform speed during the entire fuel-.

feeding operation, there will be an appreciable undesirable variation in the velocity of the fuel at the injector. To understand this point, the speed and pressure of the incoming charge should be considered, and it will be apparent that the pressure should be instantly relieved at the end of each fuelfeeding operation, for a very gradual reduction in the pressure would result in a grad ual reduction in the velocity at the nozzle. This is especially true in a system wherein the volume of the charge is determined by a valve which controls the discharge of excess fuel from the inlet passage leading from the pump to the fuel injector, the pump piston being permittedto discharge excess fuel which escapes through said valve instead of passing'to the "injector. However, in a system of this kind, the pump usually forces the fuel to the injector under a pressure of several thousand pounds per square inch, and it is obvious that a very gradual reduction of this pressure would result in a non-uniform spray at the injector and imperfect combustion of the fuel. l/Vhen the measuring valve is opened to discharge the excess fuel passing from the pump, the pressure should be instantaneously reduced to immediately discontinue the delivery of fuel through the restricted passages of the fuel injector In the ordinary systems of this type, the excess fuel passing from the pump is conducted from the measuring valve through a long restricted return duct leading back to the fuelreservoir, and even though the valve is quckly' opened, the fuel under a pressure of several thousand pounds cannot freely escape through said return duct, so the fuel is permitted to escape from the nozzle in the form of relatively large drops at the end of each fuel-feeding operation.

One of my objects is to quickly relieve the fuel pressure at the end of each fuelfeeding operation, and to thereby avoid or minimize the imperfect combustion which las heretofore resulted from a more gradual reduction of the pressure. Briefly stated, the fue1-feeding system may include.

a pump delivering excess fuel to an inlet cess fuel, the latter being returned through a duct leading to the fuel reservoir. In the preferred form of the invention, a relatively large air chamber is located adjacent to the measuring valve, and this chamber is in free communication with the intake end of the return duct. When the valve is opened, the excess fuel rapidly enters said duct, and some of this fuel freely escapes into the air chamber, so the free outlet thus established will immediately reduce the pressure to such an extent that substantially all of the excess fuel will escape through said outlet.

With the foregoing and other objects in view, the invention comprises the novel construction, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodimentof the invention. However, it is 'to be understood that the invention com-' prehends changes, variations and mod1fica-' tions which come within the scope of the claims hereunto appended.

Fig. I is a section, with some parts in ele wall of pump chamber 4 to the nozzle 3,

said passageway being formed partly by a pipe 6 which connects a block 7 to the nozzle, and partly by a passage 8 leading from the end of the pump chamber to said pipe.

The pump plunger is in the form of a tube provided with a longitudinal passage 9 for the admission of liquid fuel to the pump chamber 4 and having aninlet valve 10 at its upper end to prevent return flow of the liquid. 11 designates a spring tending to retain the inlet valve on its seat. A discharge valve 12 is located in the discharge passage 8 to prevent return of the liquid to the pump chamber.

A fuel reservoir 13 is provided with a discharge pipe 14 leading to an annular re cess 15 formed around the tubular plunger 5, the latter having ports 16 communicating with said-recess to admit the liquid fuel to p the inlet passage 9 in the plunger.

To iliustrate a suitable means for reciprocating the ump plunger, I have shown an eccentric 1% on a rotary shaft 18, a connecting rod 19 with a forked lower end mounted on said eccentric and having a curved upper end 20 seated in a socket 21 formed in a crosshead 22, the latter having a striking finger 23 adapted to engage an abutment member 24 extending from the lower end of the plunger 5. A spring 25 is interposed between the abutment member 24 and a shoulder 26 to serve as means for restoring the plunger. A spring 27 is interposed betwen a collar 28 on the crosshead 22 and a shoulder 29 to restore the erosshead,

said shoulder 29 being formed in a threaded tube 30 which serves as a stop to limit the downward motion of the plunger. The threaded tube 30 is adjustable vertically to vary the stroke of the plunger, thereby varying the quantity of liquid to be discharged from the pump.

A tubular valve guide 31 is provided with a valve 32 adapted 'to establish communication between the inlet passage 8 and a return duct '33 leading to a pipe 34 which extends into the fuel reservoir 13. A spring 35 tends to'retain the valve 32 on its seat.

To discharge the liquid through the nozzleata uniform velocity, the pump plunger should move at a uniform speed during the fuel-feeding operation, but the eccentric 17 moves the striking finger 23 at a non-uniform speed. During the beginning and end of each stroke the striking finger 23 moves at a non-unifor1n and relatively low speed, but during the middle period of the strike the speed is much greater and substantially uniform, so this middle period of. the upward stroke is preferably utilized to force the liquid fuel through the atomizing nozzle.

At the beginning of'the upward stroke, the striking finger 23 moves toward the central abutment on the member 24 at the bottom of If the plunger 5, and during the middle p0rtion of thestroke the said finger engages said abutment to actuate the plunger and force the fuel from the nozzle Thereafter, while the pump plunger continues to move upwardly at a gradually decreasing speed, the valve 32 is open to permit return of fuel from the inlet passage 8, through duct 33 to the reservoir 13. Therefore the pump plunger 5 ismoving at a substantially uniform speed while the fuel is passing through the nozzle 3, and one of my objects is to obtain a uniform velocity through the nozzle during the entire period in which the fuel is entering the combustion chamber.

During each upward stroke of the pump plunger, the inlet valve 10 is closed and liquid is drawn from the reservoir 13 to the interior of the plunger, While the discharge valve 12 is open to permit free escape of manner to measure the fuel. As an illustration of one form of adjustable operating means, I have shown the screw 38 which strikes the lower end of the valve to open the same The fuel is usually pumped to the injector 3 under a pressure of several thousand pounds per square inch,so as to effectively atomize the liquid in the combustion chamber, and this pressure should be maintained throughout the fuel-injecting operation. lVhen the valve 32 is opened to discharge the excess fuel passing'from the pump, the pressure shouldbe immediately decreased to such an extentthat no substantial amount of fuel will pass from the nozzle 3 under the decreased pressure.

Attention is therefore directed to the large air chambers '50 formed at opposite sides of the valve 32 and located adjacent thereto, said chambers being conveniently formed by drilling the block 7 and by using plugs 51 to close the lower ends of the drilled holes. The upper endof the vglve guide 31 F has a central port or passage providing an outlet port for the excess fuel discharged from the pump, and said guide is also provided with a peripheral channel 52 and radial ports leading from said central port to said channel 52. This channel is in direct communication with the return duct 33 and also with short ports '53 leading into the large air chambers 50. Consequently, when the measuring valve 32 is opened, the excess fuel under an extremely high pressure is suddenly released and divided into three streams, two of whichj'pass freely through ports 53 and into the air chambers, while the other flows through the return duct 33. The pressure is thereby quickly relieved to prevent continued discharge through the fuel 'a-t'omi zing nozzle '3. It is to be understood the nozzle may be of any suitable design with restricted passages-requiring a substantial pressure to force .liquid fuel therethrough.

The liquid fuel entering the air chambers 50 compresses the air above the liquid, and at a later period the compressed air forces the liquid through 'the ports 52 and into the return duct I claim:

1. An internal :combustion engine jprd' vided with a fuel iinjec'torhaving an passageway for the admission of liquid incl through the injector, a pump whereby the liquid fuel is forced through said inlet passageway, said passageway having an outlet for the discharge of excess fuel, said outlet being formed between said pump and injector, a valve controlling the discharge through said outlet, a return duct leading from said outlet, a pressure-reducing air chamber adjacent to said valve, and a duct leading from said return duct to said air chamber, said air chamber being in free com munication with said outlet to quickly reduce the pressure of the excess fuel. escaping therethrough. v

2. An internal combustion engine provided with a fuel injector having an inlet passage for the admission of liquid fuel through the injector, a pump whereby the liquid fuel is forced through said inlet passag'eway, areservoir through which liquid fuel is supplied to said pump, said inlet passageway havingan outlet port between said pump and injector so as to provide for the discharge of excess fuel, a return duct leading from said outlet port to said reservoir, a valve controlling the discharge through said outlet port, a pressure-reducing air chamber,

and a duct communicating with the intake end of said return duct and with said pressurea'educing air chamber whereat said valve is quickly reduced.

3. An internal combustion engine provided with a fuel injector having an inlet passage for the admission of liquid fuel through the injector, a pump whereby the liquid fuel is forced through said inlet passageway, a reservoir through which .liquid fuel is supplied to said pump, said inlet passageway having an outlet port between said pump and injector so as to provide for the discharge of excess fuel, a return duct leading from said outlet port to said reservoir, an automatic valve controlling the discharge through saidv outlet port, pressure-reducin aaiir chambers located adjacent'to said valve, :and ducts leading from said return duct to said pressure-reducing air chambers, said a .:air chambers being in free communication with said return duct and outlet port so as to quickly reduce the pressure of the excess =fuel therein. k v

testimony that I claim the foregoing I hereunto affix my signature.

. REINHARD IHILDEBRAND: 

